

ENGLISH AGRICULTURE. 103 



is thoroughly water-logged, the section of super-saturation, 

 sometimes called the reservoir, which reservoir is bounded on 

 its upper surface by what is called the " water-table." The 

 dotted line A A on the above diagram shows the water- 

 table. The upper margin or surface of the super-saturated 

 portion is called the water-table. Above the water-table suc- 

 ceeds a section of soil which is wet from capillary attraction. 

 This I have shown by direct experiment varies in thickness 

 according to the nature of the soil. Capillarity in sand does 

 not appear to raise water more than about sixteen inches, and 

 therefore for sixteen inches above the water-table we may 

 expect that in a sandy soil the section will be wet from 

 capillarity. In a very finely-divided clay capillarity appears 

 to be able to raise water about thirty-six inches; fine clay 

 soils will therefore raise water by capillarity about a yard. 

 Above the portion which is wet from capillary attraction 

 we have dry soil, unless wet from recent rains. Three 

 zones have been mentioned, the super-saturated portion, or 

 reservoir; secondly, the portion beyond that which is wet 

 from capillarity ; and thirdly, a higher portion which is dry. 

 If this dry portion does not exist, that is to say, if the water- 

 table is so near the surface that capillarity extends to the 

 surface, several evil effects will be produced. The solid saline 

 portions of the water are left on the surface. These form 

 incrustations which in some cases take place to such a degree 

 as to become a positive bar to cultivation. 



Also, when this capillary action extends up to the surface 

 a constant chilling of the soil takes place. The water-table 

 ought to be lowered artificially to such a depth that capillary 

 action cannot extend to within one foot of the surface, so 

 that we may have a dry blanket, if we may so speak, upon 

 the surface, and that the roots of plants may be able to dip 

 down easily into the portion which is wet from capillary 

 attraction, or even to the reservoir if it suits them ; but the 



